Semiconductor devices are found in many products used in modern society. Semiconductors find applications in consumer items such as entertainment, communications, and household markets. In the industrial or commercial market, semiconductors are found in military, aviation, automotive, industrial controllers, and office equipment.
The manufacture of semiconductor devices begins with formation of a wafer having a plurality of die. Each die contains hundreds or thousands of transistors and other electrical devices for performing one or more electrical functions. For a given wafer, each die from the wafer typically performs the same electrical function. Front-end manufacturing generally refers to formation of the transistors and other devices on the wafer. Back-end manufacturing refers to cutting or singulating the finished wafer into the individual die and then packaging the die for electrical interconnect, structural support, and environmental isolation.
The package has external metal contacts for transferring electrical signals into and out of the die. The die has a number of bonding pads, which are connected to the external contacts of the package by wire bonds. Wire bonding provides an electrical interconnect between the active surface of the die and bond sites on a leadframe or bond fingers on the substrate, which in turn provide connectivity to other circuitry external to the semiconductor package.
Numerous package approaches have made use of multiple integrated circuit die or package-in-package (PiP) structures. Other approaches use package level stacking or package-on-package (PoP) arrangements. Both approaches involve the stacking of two or more devices or packages within a package.
FIG. 1 illustrates one known PiP structure. Semiconductor die 12 is attached to substrate 14 with die attach adhesive 16. Bond wires 18 make electrical contact between bond pads on semiconductor die 12 and solder balls 20 to transfer electrical signals into and out of the package. Similarly, semiconductor die 22 is attached to substrate 24 with die attach adhesive 26. Bond wires 28 make electrical contact between bond pads on semiconductor die 22 and solder balls 20 to transfer electrical signals into and out of the package. An encapsulant 32 seals semiconductor die 28 to form internal stacking module (ISM) 34. A dummy spacer 30 separates semiconductor die 12 and ISM 34, and provides structural support for the package. Adhesive 38 secures dummy spacer 30 to semiconductor die 12 and ISM 34.
FIG. 2 shows a top view of an ISM with package test pads 42 and bond finger pads 44. FIG. 3a shows a top view of a double side mold (DSM) ISM with bond finger pads 46. FIG. 3b is a bottom view of the DSM ISM with package test pads 48.
There is an ever-increasing demand for semiconductor devices having more capability. The semiconductor package must be able to accommodate more semiconductor devices, i.e., greater device packing density, within the package. The aforedescribed dummy spacer requires significant space and places demands on the headroom of the package. The dummy spacer reduces the space available for semiconductor device and thereby decreases the packing density of the PiP structure.
In view of the ever-increasing need to save costs and improve efficiencies, a need exists for an integrated circuit (IC) package-to-package stacking system that provides low-cost manufacturing, improved yield, reduces the package size and dimensions, increases semiconductor device packing density, and provides flexible stacking and integration configurations for the semiconductor die.